A method of forming a capacitor of a semiconductor device which can prevent disconnection between lower electrodes by blanket-depositing a second conductive film for silicidation on a semiconductor substrate and forming an oxide of the second conductive film such as titanium dioxide (TiO2) on an interlayer dielectric using high temperature oxidation, before depositing a dielectric film, and which can obtain a high capacitance by forming both a silicide layer including the second conductive film, and the oxide of the second conductive film such as titanium dioxide (TiO2) having a high dielectric constant, on a lower electrode, and using the silicide layer and oxide as the dielectric film.